Males and females are distinguished by the presence of two claspers on the male. These claspers, although used in mating activity, are not actually used to clasp the female; rather, these are used to deliver spermatophores into the female in a similar way to a mammalian penis Fairfax , Shark Trust, Courtship behaviour and reproduction cycles have not yet been empirically studied, and current knowledge is based on limited eyewitness accounts.
In fact, there is only one peer-reviewed eyewitness account of copulation from the east coast of North America. However, perceived courtship has been reported many times with differing theories on which behaviours are related to mating. Nose-to-tail following, parallel swimming and breaching are all theorised as being linked to courtship. These behaviours have been recorded in most of the basking shark hotspots around Britain and Ireland and are closely associated with thermal fronts Sims et al, Otherwise, there is also only one recorded eyewitness account of birth by two Norwegian fishermen, Hans Goksoyr and Jonas Sordal.
The young shark was alive and immediately started swimming at the surface. As commercial fishing expanded in the s and s, basking sharks experienced an increasing number of encounters with boats and fishing gear.
The large sharks were frequently entangled in salmon gillnets and caused significant financial damage to the industry. From to , Basking Sharks in Barkley Sound were subject to an intensive and successful government eradication program. At the same time, a commercial fishery for shark livers, aggressive sport fishing, and general harassment of the sharks must have also contributed to their decline. Between the s and early s, basking sharks were only seen in large numbers in Clayoquot Sound, and even here they appear to have virtually disappeared.
Since , sightings in British Columbia waters have become increasingly rare, with only a small number of anecdotal reports from fishermen, boaters and kayakers and occasional validated reports from onboard observers on commercial vessels.
Fisheries and Oceans Canada is collecting information on Basking Shark sightings. Your information will help to determine how many Basking Sharks there are in Canadian waters and assist in programs for their recovery. In Canadian waters the basking shark is often seen during the summer and fall May to September near and around the coastline. The basking shark is a pelagic animal, occurring in both coastal and oceanic waters from to m deep, but often straying inshore.
It is commonly seen very near the surface of the water along the coast of Nova Scotia and New Brunswick in the spring and summer months.
In offshore areas, it is often found near oceanic fronts at temperatures between 7 - 16 degrees Celcius. The smallest free swimming basking shark caught was cm. The basking shark can attain lengths of at least 10 meters, but the average size is meters and may live up to 50 years. This is similar to the baleen in a filter feeding whale. Their dorsal fin is one of their most impressive features and on large sharks can be over 1m tall.
In some cases the fin flops over at the surface due to its sheer weight and height. Thankfully our sharks are now protected species. Gender can be identified by the males having two claspers under the anal fins, which vary in size and are not consistent with body size.
The maturity of such claspers varies and doesn't seem to have a direction relating to length of shark. Lampreys are a type of parasite which attach themselves to the same area and can sometimes be mistaken for claspers when we are tying to identify the sex.
How and where these lampreys attach to the sharks is unknown. Another fact which is relatively unknown about basking sharks is that they do have teeth. They are formed on two cusps on the upper and lower jaw with numerous rows and hundreds of individual teeth. They are only mm long and hooked backwards.
Although they are not used in feeding, they may be used for mating and we have seen scarring on the fins that may indicate this.
There is also a suggestion that they are used in oophagy intra-uterine cannibalism. To quote the famous poem by Norman MacCaig 'That roomsized monster with a matchbox brain'.
Compare this to a great white shark who has to actively hunt and engage strategy balanced with a high energy seal diet. In basking sharks, the nerval mass for smell is actually much larger than the brain, indicating that this has far greater importance and is likely to be used in hunting plankton. The eyes are large and black and eyesight is thought to be fairly poor.
It is unlikely that the sharks use eyesight to find plankton in the water but probably use this sense for object avoidance and light level detection. The liver is the biggest organ in their body and can form between a quarter and third of their body weight. It contains an oil called squalene and is used as an energy source possibly for use during their long migration pattern or times of low plankton abundance and also for buoyancy in the water as sharks do not have a swim bladder like bony fish.
Unfortunately this large organ was one of the reasons why they were extensively hunted as the oil was used in many different industries. Like other sharks their skin is formed from placoid scales called dermal denticles. They are similar to shark teeth, covered with a hard enamel and are interlaced like tiles on a roof. These scales are designed for maximum hydrodynamic function so they can move through the water with the most efficiency, along with providing some protection for the shark.
If touched they feel very rough in one direction and smooth in the other. The colour of the sharks can vary but they are usually a dark grey with different patterns and markings along their flank. Basking sharks have an unusual classification and are part of the order Lamniformes. This order is more commonly known as the mackerel sharks and ranges from great whites to makos, porbeagles and the megamouth. It seems strange to think that the famous seal hunting great white is related to the plankton eating basking shark, however they share a similar fin and body type.
Jump to navigation. The basking shark is the second largest fish in the world, and like the largest fish the whale shark and the largest animal the great whales , basking sharks are filter feeders that eat tiny, planktonic prey.
Reaching lengths of 40 feet 12 m and resembling predatory sharks in appearance, the basking shark can give an intimidating impression, but they are quite harmless. They spend most of their time near the surface, swimming with their extraordinarily large mouths open, filtering out their preferred prey, but they may also make deeper, feeding dives.
Pairs of basking sharks mate via internal fertilization, and females give birth to live young. As opposed to whale sharks , which give live birth to hundreds of small babies, basking sharks give birth to only a few, quite large babies.
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